Closing devices for belts



Sept. 26,- 1967 P. M. BAYON CLOSING DEVICES FOR BELTS 3 Sheets-Sheet l Filed May 10, 1965 n QN,

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ll .I hi hl l! il i Sept. 26, 1967 P. M. BAYON CLOSING DEvIcEs Eon BELTS 5 Sheng-shea 2 .l u Amar/ng y SePt- 26 1937 P. M. BAYoN 3,343,873

CLOSING DEVICES FOR BELTS Filed May 10, 1965 3 Sheets-Sheet 5 )4. n, h f:

fm1-m. Maffe /fyon A'Hw rMLy United States Patent C 3,343,873 CLOSING DEVICES FOR BELTS Patrice Marie Bayou, Le Prieure, Angers, Maine-et-Loire, France Filed May 10, 1965, Ser. No. 454,327 Claims priority, applicatie; France, Apr. 9, 1965, 12 7 3 10 claims. (ici. 297-385) ABSTRACT F THE BISCLSURE The present invention relates to novel closing devices for belts, straps and similar attachments, particularly but not exclusively for security belts for passengers in automobiles, airplanes and other vehicles. These novel devices are strong and eflicient, but their simple conception permits the relatively cheap manufacture of assemblies satisfying the different standards of safety required with respect to the resistance of the closure to the various efforts which may be applied, especially by traction, and with respect to the ease and rapidity of opening and release.

The devices of this invention comprise a rigid casing or frame having a U-shaped cross-section, consisting of a center plate and of two parallel sides which maintain at least two inner anchoring means around which the xed end of the belt is looped, while the free, movable end of the belt is adjustably engaged in a coupling plate which can engage the casing through one open end thereof and in the center plate of which there is provided a cut-out opening for the engagement and locking of a lock formed out of a manually operated lever pivotably mounted in the case, against the deformations of the end loop of the belt on which said lever acts through a transverse boss formed at the end of the lever away from the lock.

The foregoing characteristics and other features of the invention will appear from the following description and from the attached drawings in which:

FIG. 1 is a vertical cross-section of a device according to the invention, taken along the length of the closing device.

FIG. 2 is a sectional plan View taken on line II-II of FIG. l.

FIG. 3 and FIG. 4 are cross-sectional elevations taken respectively on lines III and IV of FIG. l.

FIG. 5 is a vertical cross-section illustrating one of the characteristic positions of the elements of the device shown in FIGS. 1 to 4, said position being that of engagement of the free end of the belt and of the plate, before locking.

FIG. 6 is a vertical cross-section of a second device according to the invention.

FIG. 7 is a transverse cross-sectional elevation taken along line VII-VII of FIG. 6.

FIG. 8 is a vertical cross-section showing a variant of the embodiment illustrated in FIG. 6.

FIG. 9 is a vertical cross-section showing another ernbodiment of a device according to this invention.

FIG. 10 is a sectional plan view taken along line X-X of FIG. 9.

1 rectangular. Plate 19 is provided,

3,343,873 Patented Sept. 26, 1967 ICC FIG. 11 is a 4transverse cross-section taken along line Xl-XI of FIG. 9.

FIG. 12 is a sectional plan view showing a further embodiment of this invention.

FIG. 13 is a longitudinal cross-section taken along line XIII-XIII of FIG. 12.

FIG. 14 is an elevational cross-section of another embodiment of this invention.

It will be understood that the embodiments illustrated are not to be taken as limiting the scope of this invention.

According to the rst embodiment illustrated in FIGS. 1 to 5, the device comprises two parts 1 and 2 which complete each other and cooperate, respectively mounted on the ends 3 and 4 of a safety belt, strap or other similar attachment 5.

Element 1 comprises a rigid casing so formed as to pre-sent a crosssection shaped as an inverted U, the parallel sides 6 of which support, about midway of their height, an axle 7. The latter forms a pivot around which there is slipped a bearing 8 formed at one end of a lever 9. Said lever 9 is a locking and unlocking lever, the actuating part 10 of which extends through a cut-out 11a provided in the center plate 11 of the casing. -On the surface of the locking and unlocking lever 9 facing the center plate 11, there is formed an abutment or hooking lock 12, approximately prismatic, defined by an inclined ramp 13 originating at the level of bearing 8, said ramp being connected to a steep face 14. Lever 9 also comprises, opposite to lock 12, a transverse boss 15, preferably convex, spaced from bea-ring 8, and which cooperates with an end loop 16, in the intermediate portion thereof, said loop 16 being integral with the end 3 of the `belt and attached thereto by stapling or stitching.

A shaft 17, transverse to casing 1, is supported by sides 6 at one end thereof and is located in a plane lower than that of axle or pivot 7; a second shaft 18, also transverse to casing 1, is supported by sides 6 near the opposite end thereof and is loca-ted in the same plane as axle or pivot 7. The length of loop 16 is suflicient for allowing it to be threaded or slipped over and around both shafts 17 and 18. The location of shafts 17 and 18 is so selected in two different planes that loop 16 has a portion contacting and lbending around the semi-cylindrical bearing 8, so that the tension normally applied to the belt-end 3 in -use in the direction of arrow f1 is transmitted to said loop which then tends to push back the transverse boss 15,

and therefore lever 9, in the direction in which lock 12 canpivot toward the internal face of ing 1.

'Element 2 consists of a coupling center plate 11 of casplate 19, substantially in the region of its useful portion of penetration into casing 1, with a window 20, also rectangular, and the length of which corresponds to that of lock 12. Coupling plate 19 comprises also, at a distance back of window 20, lateral sides 21, curved downwards, which ldefine semi-circular slides 22 (FIG. 3). Slides 22 are guiding and supporting elements for arms 23 4 of the belt is looped.

As can be seen from FIG. 2, the width of the portion of the coupling plate 19 which is provided with curved sides 21 corresponds substantially to the distance between the inner faces of sides 6. Therefore, the degree maximum of penetration of the useful portion of plate 19 is determined by the abutment of sides 21 against sides 6. This penetration is so selected that the forward transverse edge of window 20 can engage the steep face 14 of lock 12, which, upon such engagement, forms a stop opposing the uncontrolled disengagement of the coupling plate 19- from the casing 1. The efliciency of the stop-forming lock 12 is increased, as stated hereinabove by the traction of use applied to loop 16 through that exerted in the direction of arrow f1 to the belt-end 3. Thus, that traction causes a stress and extension of loop 16 and therefore, presents a resistance opposing any possibility of pivotrnent of locking and unlocking lever 9 around its pivot 7 in the direction of arrow f2.

It must be noted that, as shown in FIG. l, the position of axle 18 is also selected in order that, taking into account the thickness of the belt looped around it, said axle forms a support for plate 19 when the latter is in locking position with lock 12. Such support reduces substantially the magnitude of the stresses which can be applied to plate 19 in the direction of arrow f3 and contributes in increasing the efficiency of the blocking and retention of said plate 19 inside casing 1.

When the user wants to cause the unlocking and the separation of the two cooperating elements 1 and 2, he merely presses on the actuating part 10 of lever 9, to cause the latter to pivot in the direction of arrow f2 against the resistance of loop 16. As can be seen on FIG. 5, the pivoting of lever 9, which can be effected with a single hand, lowers lock 12 sufficiently to retract the steep face 14 out of the forward edge of window 20. Plate 19 can then be removed from casing 1 in the direction of arrow f4.

In order to carry out with certainty the engagement and the mutual locking of coupling elements 1 and 2, the user places plate 19 opposite casing 1 to cause by simple pressure or push in the direction inverse to that of arrow f4 the penetration of the plate within casing 1 between center plate 11 and axle 18. The end portion of plate 19 is brought in contact with the rising ramp 13 of lock 12 and climbs over said ramp, while exerting simultaneously a pressure tending to cause the slight pivoting of lever 9 against the resistance of loop 16. When the complete engagement has been obtained, the initial tension of loop 16 brings lever 9 back to its initial position, in which lock 12 enters window 20 and opposes the disengagement of plate 19.

FIGS. 6 and 7 illustrate a second embodiment of the device object of this invention. According to said second embodiment, the sides 6 of casing 1 support, at equal distance from their transverse edges, two axles 26 and 27 located in the same plane relatively to plate 19. As in the embodiment described for FIGS. l to 5, axles 26 and 27 are also adapted to receive loop 16 of the belt end 3. Axle 27 forms also a pivot for a semi-cylindrical, open, bearing 28 formed at the end of lever 9 and fitted over the portion of loop 16 which is wound around said axle 27. The open, semi-cylindrical bearing 28 is directly contiguous with a boss 29, similar to the transverse boss of FIGS. 1 to 5, and tending to provoke the deformation of loop 16 against the initial tension of use -applied to belt end 3 according to arrow f1. This tension insures, in the normal state, that lever 9 is maintained in a locking position in which lock 12 is brought against the internal face of center-plate 11 of casing 1. In this embodiment, the centerplate is provided, instead of the cut-out 11a, with a window 30 through which the actuating part 10 of lever 9 projects outwardly. The opening of the semi-cylindrical bearing 28 of said lever 9 is evidently so oriented as to avoid any foituitous disengagement of said lever from axle 27, especially in the locking position.

The device built as described .above operates obviously in the same manner as that described with reference to FIGS. l to 5. However, it must be noted that lever 9 is subjected to cleaner and faster reactions of adjustment, since its boss 29 acts more forcibly in the direction in which it deforms the loop 16 against the initial tension of use applied in the direction of arrow f1. Moreover, the locking qualities of plate 19 are substantially bettered by the fact that the stresses applied in the direction of arrow f5 to the belt-end 4, and therefore to plate 19, during use, are transmitted by the forward edge of window to the steep face of lock 12, in the direction in which they tend to maintain firmly lever 9 against center-plate 11 of casing 1.

A modification of the device according to FIGS. 6 and 7 is shown in FIG. 8. According to this modification, the sides 6 of case 1 support only one axle 31, disposed substantially in the same manner as axle 27 of FIGS. 6 and 7. Axle 31 is also for retaining loop 16, which is passed at its upper part 16a through window 30 of center-plate 11, to pass around a transverse rigid wall portion 32 extending between sides 6. The modication just described exhibits an eiciency and a precision for locking and unlocking greater than those found in the embodiment of FIGS. 6 and 7, since the initial tension applied to loop 16 acts simultaneously on the transverse boss 29 and on the angular portion 33 which constitutes the contact zone or link between lever 9 and actuating part 10. In addition to this particular advantage, it must also be noted that the conception of this embodiment is much simpler than those of the embodiments of FIGS. l to 7 and permits, therefore, a less costly manufacture.

FIGS. 9 to 11 illustrate another embodiment of the devices object of this invention. In this embodiment, simpler than the preceding ones, casing 1 is provided with sides 6 which are extended into turned-in flanges 34, which form with sides 6 sliding runways 35. The latter are provided to guide and support a metallic polygonal frame 36. Said frame 36 is normally fitted in loop 16 of belt-end 3 in order that its sides 36a, transverse to the direction of engagement in casing 1, form supporting means around which loop 16 is wound. The side 36a, which is forward in relation to the direction of engagement in casing 1, forms also, since it is at the rear end of casing 1, according to arrow f1, a pivot over which is fitted, on top of the wound loop 16, the partly opened, semi-cylindrical bearing 2S formed lat the end of the locking and unlocking lever 9. It is apparent that the lever 9 is placed on the corresponding pivot 36a, just referred to, before the fitting of the frame 36 and of loop 16 in the runways 35 of casing 1. As in the previous embodiments, the locking and unlocking lever 9 forms, in a plane adjacent to the open, semi-cylindrical, bearing 28, a transverse boss 29 on the upper side of loop 16.

To insure the engagement of frame 36, of loop 16 and of lever 9 within casing 1, it is necessary that the actuating portion 10 of lever 9 be subjected to a pivotment in the direction of arrow f2 in order to lower the lock 12 by a definite distance allowing the engagement of lever 9 under the center-plate 11 of casing 1. Such pivoting in the direction of arrow f2 tends obviously to cause, through transverse boss 29, the deformation of the upper strand of loop 16. The additional tension applied to the latter is relieved after the definite engagement of lever 9 under center-plate 11 and subjects lever 9 to a pivoting in a direction opposite to that of arrow f2. The dimensional characteristics of casing 1, and particularly the spacing provided between the turned-in flanges 34 and the center-plate 11, are so determined that the reaction of loop 16 applies lock 12 against the internal face of said center-plate and insures that frame 36 be maintained inside casing 1, more particularly in the casing when the device is not used to insure the closing and the liaison of belt-ends 3 and 4. Indeed, in the case to the contrary, the tensions of use, according to arrows f1 and f5, applied respectively to beltends 3 and 4, interlock lever 9 and plate 19, so that casing 1 cannot be subjected to any relative sliding since it is wedged, on the one hand, against the actuating part 10 of lever 9 and, on the other hand, against the shoulders 37 provided in plate 19 to limit the amplitude of penetration of its useful portion cooperating with lock 12.

Also, in order to simplify the construction of the plate, the longitudinal portion extending beyond shoulders '37 is machined to present two parallel, transverse slots 38, the spacing of which is selected to encompass a rigid bar 39 around which there is wound a loop 40, formed by the free end of belt-end 4.

The operations of locking and unlocking, causing respectively the coupling or the disengagement of parts 1 and 2 are effected in the same manner as has been described heretofore. This construction is similar to that described with respect of the embodiment of FIGS. 1-5 and that of FIGS. 6-7, in which the bar is numbered 24, and the transverse slots 24a. The same construction applies to the embodiment of FIG. 8.

The length of the belt between ends 3 and 4 is adjusted, in the embodiments of FIGS. 1 to 11 by slipping end 4, before stapling or stitching the loop formed around elements 24, through slots 24a (FIGS. l-S), or around element 39, through slots 38 (FIGS. 9-11), and pulling on one of its strands in the direction of arrow f4 (FIG. 5) or f5 (FIGS. 6, 8 and 9), thereby lengthening or shortening the belt according to the size of the user.

As shown in the embodiments illustrated in FIGS. 6 to 10, the actuating portion of lever 9 is preferably provided with transverse serrations, to avoid that the hand of the user should slip unintentionally.

FIGS. l2 and 13 illustrate another embodiment of the device object of this invention, in which casing 1 is still provided with sides 6 extended 'by turned-in flanges 34. The latter are cut in the transverse portion of the casing 1 through which plate 19 is introduced and they form ridges 41 forming stops against which rests the turned-up flange 42 of a base-plate 43. The latter, which is shaped substantially as a U, has a second raised or turned-up fiange 44, parallel to turned-up flange 42 and the end portions of which are cut to form tongues 45, slightly inclined inwardly, in order that the distance between them and raised or turned-up flange 42 be smaller than the length of the turned-in flanges 34 of the casing.

The turned-up fiange 42 of base-plate 43 extends into a cylindrical part 46, provided to form bearing around which the loop 16 of belt-end 3 is partially wound, beltend 3 has its lower portion surrounding completely the base-plate 43. Bearing 46 serves also as a pivot over which the open semi-cylindrical bearing 28 of locking rand unlocking lever 9 is fitted on top of belt-loop 16. As in the preceding embodiments, lever 9 includes a lock 12 and 'a boss 29 acting on the tensioned portion of the loop between bearing 46 and the parallel turned-up flange 44.

To mount the base-plate 43, the loop 16 and the lever 9 inside case 1, bearing 46 is engaged at the level of turned-in flanges 34 in order that the turned-up flange 42 come to bear on ridges 41. In that position, it is sufficient to bring closer together the case 1 and the base-plate 43 so that the tongues 45 can cooperate with the corresponding transverse zones of the turned in flanges 34. Locking is obtained through a temporary relative pressure which deforms elastically tongues 45 t0 cause their engagement behind the turned-in flanges 34. Casing 1 and base-plate 43 are then locked together and lever 9 is :placed inside, its actuating part 10 being at least apparent or accessible at the level of window 30.

As appears from FIG. 12, the cut-out of turned-in iianges 34, forming ridges 41 permits to protect the semicylindrical bearing 28 of lever 9 and primarily to dispose, slightly recessed, the inclined ramp 13 of lock 12 which form thus, with the inner face of center plate 11, a passageway facilitating the introduction of coupling plate 19.

The operation of the embodiment described above with respect to FIGS. 12 and 13 is the same as that of the embodiments previously described.

FIG. 14 illustrates another embodiment of the device according to the invention. In this embodiment, casing 1 contains la fulcrum 50, which can be a fixed or removable axle carried by the sides 6 or by a metallic rigid frame such as frame 36 of the embodiment of FIG. 10. This fulcrum constitutes a :pivot for the open semicylindrical bearing 28 of lever 9 which is tted over a tubular part 51 Which is itself fitted over fulcrum S0.

Tubular part 51 is formed by a spring 52, for instance a metal spring. Spring 52 -has an arm 53 folded over and acting directly on lever 9 in the direction in which said lever is maintained in the locking position. It is evident that spring 52 must be set in a location which permits it to act on lever 9. Such setting can be directly on pivot Si), as shown; or casing 1 may include turnedin flanges 34 on which spring 52 rests.

This invention is not limited to the embodiments described in detail, since some modifications can be brought thereto without departing from its scope.

Having now described my invention, what l claim as new and desire to secure by Letters Patent is:

1. A closing device for belts including a free belt endportion, a fixed belt end-portion, :a buckle attached to said fixed belt end-portion and means in said buckle for releasably locking said free belt end-portion in said buckle, said device comprising in combination:

(a) a rigid casing having an inverted U-shaped cross section and consisting of a center-plate, said casing having two open ends and of two fianged parallel sides extending from said center plate;

(b) at least two transverse anchoring means maintained by said parallel sides and around which the fixed belt end-portion is looped;

(c) a coupling plate in which the free belt end-portion is adjustably engaged and which is adapted to engage said casing inside the latter through one of its open ends;

(d) a manually operated lever pivotally mounted around a transverse pivot supported by said sides of said casing and comprising an actuating part, locking means protruding upwardly from the upper face of the intermediate portion of said lever and a transverse boss formed downwardly at the end of said lever opposite said actuating part, between said locking means and said pivot, said lever acting on said looped fixed belt end-portion through said boss against deforming reactions of said end-portion;

(e) a cut-out window in said coupling plate for engaging and disengaging said locking means;

(f) a cut-out opening formed in said center-plate at the end thereof away from said pivot, and through which said lever is engaged inside said case and from which said actuating part protrudes.

2. A device as claimed in claim 1, in which said anchoring means consist of two transverse shafts spaced from each other and located in different planes, said lever comprising a bearing fitted around said pivot, said planes 'being so selected that the upper face of said looped fixed belt end-portion contacts and bends around said bearing.

3. A device as claimed in claim 2, in which said pivot and one of said transverse shafts are combined into a single element, and in which said bearing is semi-cylindrical and partially opened at its lower portion, said looped fixed belt end-portion fitting directly around said single element, and in which said lever is fitted onto said single element through said partial opening over said looped fixed belt end-portion.

4. A devi-ce as claimed in claim 1, in which said anchoring means consist of a single transverse shaft located at the end of said lever away from said actuating part and of a transverse rigid Wall portion extending between said parallel sides at the end of said cut-out opening of said center-plate away from said transverse shaft, said fixed belt end-portion being looped around said transverse shaft and said wall portion, said pivot and said shaft forming a single element, said lever comprising a bearing, semi-cylindrical and having an opening at its lower portion, said looped fixed belt end-portion fitting directly Iaround said single element, and in which said lever is fitted onto said single element through said opening over said looped fixed belt end-portion.

5. A device as -claimed in claim 1, in which said coupling plate is extended into two curved, substantially semi-cylindrical, lateral sides forming two slides; said device comprising further a transverse bar slidingly supported at each of its ends by one of said slides, said free belt end-portion being adjustably engaged in said coupling plate between said slides and looped around said transverse bar.

A6. A device as claimed in claim 1, in which said sides of said rigid casing comprise, vat their free edges, an inwardly directed ilange forming with said sides runways; in which said anchoring means are the two bars, trans- Verse to said casing, of a metallic polygonal frame adapted to slide in and out of said case on said runways, for engagement in and disengagement from said case; s-aid xed belt end-portion being looped around said two transverse bars; said lever having at its end away from said actuating part ,a cylindrical bearing having a partial opening at its lower portion; said bearing engaging, through said partial opening, and over said iixed belt end-portion the transverse bar of said frame which has its axis in the plane containing the axis of said bearing when said lever is fully engaged within said case and said frame is also fully engaged in said case, the transverse bar last mentioned forming thereby an anchoring `means and la pivot around which said lever is pivotable.

7. A device as claimed in claim 6, in which two parallel transverse slots are cut in said coupling plate, said slots being spaced from each other to encompass a transverse bar around which the free belt end-portion is looped.

8. A -device as claimed in claim 1, comprising further:

(a) turnedain flanges extending from the free edges of said sides of said case, said flanges extending from the forward edge, considered in the direction of engagement of said coupling plate in said casing, of said sides to a distance from the rear edge of said sides, said anges forming stopping ridges at their rear end;

(b) a U-shaped base-plate having a forward and a rear turned-up liange, said baseaplate laying against the underside of said turned-in anges; said forward turned-up ilange abutting the forward edge of said turned-in iianges; said rear turned-up flange abutting said stopping ridges and being terminated at its top by a cylindrical bearing transverse to said case;

(c) said iixed belt end-portion being looped around said bearing, said rear turned-up flange, said baseplate and said forward turned-up ange, the lower portion of said loop surrounding completely said `base-plate on its outside, lower surface;

(d) said lever having, at its end Aaway from said actuating part, a cylindrical bearing having a partial opening at its lower portion, said bearing engaging, when said lever is fitted inside said case, through its partial opening and over said xed 'belt end-portion, said bearing of said rear turned-up iiange, said last named bearing forming also a pivot around which said lever is pivotable.

9. A device as claimed in claim 1, in which said anchoring means comprise a fuicrum transverse to said casing and maintained by said sides of said case near the rear end of said case away from said cut-out opening, and an elongated resilient spring one end of which is looped around said fulcrum and the other end of which has an arm folded over and back in the direction of said fulcrum; said sides of said case having, at their tree edges, turned-in flanges; said spring resting on said turned-in flanges; the fixed belt end-portion being looped around said fulcrum and said spring; said lever having, at its end away from said actuating part, a bearing with a partial opening at the lower portion thereof, said bearing being adapted to engage, through said partial opening, when sai-d lever is tted in said casing, said fulcrum over said looped xed belt end-portion, said fulcrum forming a pivot around which said lever is pivotable.

10. A device as claimed in claim 1, in which said coupling plate comprises, relatively to its direction of engagement in said casing, a rear portion rearward of said cut-out window and a forward portion in which said cut-out window is provided, said rear portion having a transverse dimension substantially equal to that of said casing and said forward portion having a transverse dimension slightly smaller than the dimension between the inner faces of said sides of said casing, said rear portion thereby having two shoulders between its rear and forward portions, said shoulders being adapted to limit the amplitude of penetration of said forward portion inside said casing.

References Cited UNITED STATES PATENTS 1,521,439 12/1924 Forsell 24-78 2,590,851 4/1952 Elsner 24-230 2,690,601 10/1954 Van Buren 24-78 2,710,999 6/1955 Davis 2li-230.1 3,233,296 2/ 1966 Whittingham 24--230.1

FOREIGN PATENTS 1,052,824 3/1959 Germany.

BOBBY R` GAY, Prim-ary Examiner. D. I. WILLTAMOWSKY, I. T. MCCALL, Examiners. 

1. A CLOSING DEVICE FOR BELTS INCLUDING A FREE BELT ENDPORTION, A FIXED BELT END-PORTION, A BUCKLE ATTACHED TO SAID FIXED BELT END-PORTION AND MEANS IN SAID BUCKLE FOR RELEASABLY LOCKING SAID FREE BELT END-PORTION IN SAID BUCKLE, SAID DEVICE COMPRISING IN COMBINATION: (A) A RIGID CASING HAVING AN INVERTED U-SHAPED CROSS SECTION AND CONSISTING OF A CENTER-PLATE, SAID CASING HAVING TWO OPEN ENDS AND OF TWO FLANGED PARALLEL SIDES EXTENDING FROM SAID CENTER PLATE; (B) AT LEAST TWO TRANSVERSE ANCHORING MEANS MAINTAINED BY SAID PARALLEL SIDES AND AROUNND WHICH THE FIXED BELT END-PORTION IS LOOPED; (C) A COUPLING PLATE IN WHICH THE FREE BELT END-PORTION IS ADJUSTABLY ENGAGED AND WHICH IS ADAPTED TO ENGAGE SAID CASING INSIDE THE LATTER THROUGH ONE OF ITS OPEN ENDS; (D) A MANUALLY OPERATED LEVER PIVOTALLY MOUNTED AROUND A TRANSVERSE PIVOT SUPPORTED BY SAID SIDES OF SAID CASING AND COMPRISING AN ACTUATING PART, LOCKING MEANS PROTRUDING UPWARDLY FROM THE UPPER FACE OF THE INTERMEDIATE PORTION OF SAID LEVER AND A TRANSVERSE BOSS FORMED DOWNWARDLY AT THE END OF SAID LEVER OPPOSITE SAID ACTUATING PART, BETWEEN SAID LOCKING MEANS AND SAID PIVOT, SAID LEVER ACTING ON SAID LOOPED FIXED BELT END-PORTION THROUGH SAID BOSS AGAINST DEFORMING REACTIONS OF SAID END-PORTION; (E) A CUT-OUT WINDOW IN SAID COUPLING PLATE FOR ENGAGING AND DISENGAGIGN SAID LOCKING MEANS; (F) A CUT-OUT OPENING FORMED IN SAID CENTER-PLATE AT THE END THEREOF AWAY FROM SAID PIVOT, AND THROUGH WHICH SAID LEVER IS ENGAGED INSIDE SAID CASE AND FROM WHICH SAID ACTUATING PART PROTRUDES. 